Very true, I had it when Charles first bring it in last year and its only grow 2" since then. Maybe because I don't feed it enough. The fish look more better out of the water because of the scale. Now I just want ray and aro only.I have an L152 that's 6 inches. They're pretty cool, but a bit secretive. They are not many keepers of them, so no one knows how big they really get in captivity. I suspect the 20" is from a wild caught specimen. Either way, it'll take years for it to get to even a foot I believe. I'm sure once you get it to a monstrous size, someone would be willing to take it off your hands. These are not like commons and sailfins which are a dime a dozen and grow to a foot in 2 years.
If you want it, get it. I'm sure you'll like it.